[1973ramairman]

Going to replace my heads with a new set of edelbrock aluminum's , so which ones to use ? D- port out of the box or the fast burn cnc chambers?
Round port out of the box or the fast burn cnc chambers ?
Also which new headers should I use? Been looking at Hooker competition but they say the port shape is same as port ? What does that mean ? Same headers for both round and D port?
Engine
73 455 block 30 over BUTLER short block all upgrades
Pistons have a 14 cc dish so with new 72 cc heads my new compression should be around 9.98:1 at 0 deck
Cam is a lunati voodo 268/276 flat tappet
Intake is a edelbrock performer
Carb is a factory Rochester size ? Had rebuilt by Cliff for my combo at the time ( same as above but with 1970 455 ho heads) with a compression of 9.5:1
Car is a 1973 GTO

[RocktimusPryme]

Performance wise, the shape of the ports doesnt make a ton of difference. The question has been asked a few times, I asked it myself. Maybe once you get to extreme levels over in the race section, but for street cars up to about 600 HP. Doesnt matter D port vs Round. For sure if you have the choice get the new heart shaped chambers.

What you actually need to do, is decide what you want to do for exhaust for sure, and make sure its available for your car in either port shape. For instance I wanted to use RARE Long branches. Turns out after I bought my RP heads, that they arent currently making those manifolds for first gens. So I kinda got backed into headers.

[Steve Barcak]

For the investment you are going to do, be wise and buy the Ram Air IV/455HH/SD style round port exhaust.
The bolts are spaced much further apart and more evenly. This makes working on them much more pleasant. I would rarely suggest buying alum d ports for that reason alone. you will be happy you did.

[cdrookie]

2nd gen firebird headers will fit your car. I have a 75 lemans and had round port hedman hustlers, for a 2nd ten bird, and they fit great. I have OBX on there now, and for the price they can't be beat, but you will probably have to dent a tube or so to get them to fit just right. So from a price standpoint, round port with stainless OBX headers would be cheaper than D port's with good coated(or stainless) headers. I'd get rid of that Performer intake also.